Melt-quenched carboxylate metal-organic framework glasses

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) are typically built using carboxylate ligands, but forming MOF glasses usually requires azole- or weakly coordinating ligands.
• Strong coordination in carboxylate-based MOFs impedes the thermal vitrification process, hindering the creation of MOF glasses.

Purpose of the Study:

• To investigate the formation of carboxylate-based MOF glasses.
• To explore the properties of these novel MOF glasses, particularly their melting points and mechanical characteristics.

Main Methods:

• Synthesis of melt-quenched MOF glasses using Mg2+ or Mn2+ with adipate, an aliphatic carboxylate ligand.
• Characterization of the melting temperature (Tm) and mechanical properties (hardness, elastic modulus) of the resulting MOF glasses.

Main Results:

• Successfully produced carboxylate-based MOF glasses with low melting temperatures (284°C for Mg2+ and 238°C for Mn2+).
• These MOF glasses demonstrated superior mechanical properties, including enhanced hardness and elastic modulus, compared to existing zeolitic-imidazolate framework (ZIF) glasses.
• The low Tm is attributed to the flexible, low-symmetry adipate ligand and the absence of crystal field stabilization energy in the metal ions.

Conclusions:

• This study demonstrates the feasibility of creating carboxylate-based MOF glasses.
• The developed MOF glasses offer a promising pathway for integrating a wider range of carboxylate-based MOFs into glass materials.
• The findings pave the way for new applications of MOF glasses with tunable properties.